T cells expanded from PD-1+ peripheral blood lymphocytes share more clones with paired tumor-infiltrating lymphocytes.

Both tumor-infiltrating lymphocytes (TIL) and PD-1+ peripheral blood lymphocytes (PBL) are enriched for tumor-reactive clones recognizing known and unknown tumor antigens. However, the relationship between the T-cell receptor (TCR)-β repertoires of the TIL and T cells expanded from paired PD-1+ PBL and whether T cells expanded from PD-1+ PBL can be used to treat patients with cancer as TIL substitutes remains unclear. Here we established a highly efficient protocol to prepare polyclonal T cells from PD-1+ PBL. A functional T-cell assay and tetramer staining revealed that cells from PD-1+ PBL were relatively enriched for tumor-reactive T cells. Furthermore, deep TCR-β sequencing data revealed that an average of 11.29% (1.32%-29.06%, p=0.015, n=8) tumor-resident clonotypes were found in T cells expanded from paired PD-1+ PBL, and the mean accumulated frequency of TIL clones found in T cells expanded from PD-1+ PBL was 35.11% (7.23%-78.02%, p=0.017, n=8). Moreover, treatment of four patients, who failed multi-line therapy and developed acquired resistance to anti-PD-1, with autologous T cells expanded from PD-1+ PBL combined with anti-PD-1 antibody elicited objective responses from three of them. These results indicate that T cells expanded from PD-1+ PBL share more clones with paired TIL and could be used to treat patients with cancer as TIL substitutes.